[LAU] OT - Audio and Video Synch

[Ralf Mardorf]

On Fri, 2013-10-18 at 16:23 -0700, Len Ovens wrote:
> On Sat, 19 Oct 2013, Ralf Mardorf wrote:
> 
> > On Fri, 2013-10-18 at 15:38 -0700, Len Ovens wrote:
> >> So if you are looking from a distribution POV, you have no control of
> >> what the audience will play your video on.
> >
> > Assumed you would have the perfect player, the picture is absolutely
> > identical to the original, the sound is completely equal to it's source,
> > on every consumers gear, then light still is faster than sound. Do you
> > sync for the smart phone or for the drive-in theater?
> 
> Yes of course. The brain is used to dealing with audio lag at varying 
> distances. I was playing around with VLC which has a sync control. It 
> seems I could set it to be off a bit but my brain seems to correct it with 
> in some seconds... Or maybe every time I change the sync the audio and 
> video restart from a known point of sync and then drift...
> 
> As you said before, the brain notices leading sound much sooner than 
> lagging sound. That would be the way it is in nature. The drive-in 
> theaters I have seen have in-car sound (often using the car's radio), so 
> the delay is minimal. I wonder if indoor theater operators set the audio 
> ahead just a bit so it hits the second or third row in sync. It would 
> probably mess with the surround sound too much. I will say I have not 
> noticed sync problems in the theater even though we always sit at the back 
> as my son doesn't see well above horizontal.

For flash and thunder the brain can't compensate it. Sometimes it
happens that I watch TV for 30 minutes without noticing bad sync, if I
randomly notice the delay, I often can't continue watching. It's similar
to concave vs convex for a drawing. Sometimes it seems to be convex,
sometimes concave and sometimes it's switching.